The present invention relates to a paint spraying device and more particularly to a high volume, low pressure device to pattern shape the atomizing and fan air.
Paint spray devices, or guns, were usually operated at high pressure to atomize the paint and to adjust the spray patterns due to the wide availability of high pressure air. However, the coating transfer efficiency was less than optimum at the high pressures and an undesirable amount of coating material was dispersed into the environment. This led to an increased use of high volume low pressure (HVLP) air operated spray guns due to improved coating transfer efficiency and decreased air pollution. Several approaches have been used to provide the low pressure air and also have high volume air flow. Some of these are disclosed in the following:
Also, variations have been proposed for the configuration of a cap to direct the flow of the fan air and the atomizing air to form the spray pattern of the paint as in the following:
However, there still remains a need for improved paint spraying devices, especially devices which can be used in electrostatic painting procedures.
It is an object of the invention to provide a more efficient high volume low pressure device for spraying paint.
It is a further object to provide very compact device which has high access to confined areas when the device is attached to a robot arm.
In accordance with the teachings of the present invention, there is disclosed a device for spraying paint with a body having a first end and an opposite second end. A nozzle is attached to the first end of the body. Means are provided for introducing fan air and atomizing air into the body, and means are provided for controlling the flow of paint through the device. At least one slot for the atomizing air and at least one slot for the fan air are formed in the body for exiting of the respective atomizing air and fan air from the first end of the body such that low pressure air is applied to the paint and high volume atomized paint is provided by the device.
Further in accordance with the teachings of the present invention, there is disclosed a device for spraying paint with a body having a first end and an opposite second end. Means are provided for introducing fan air and atomizing air into the body. A replaceable cartridge is disposed in a center bore in the body, the cartridge having at least one piston, a needle valve, and at least one spring. Activation of the at least one spring moves the needle valve and the at least one piston to introduce paint, atomizing air and fan air into the device.
In another aspect, there is disclosed a device for spraying paint having a body connected to a nozzle, an air cap covering the nozzle, an air cap nut securing the air cap to the body and means for controlling the flow of paint, atomizing air and fan air through the body. An improvement provides means for directing a portion of the fan air between the air cap and the air cap nut such that fan air passes over an outer surface of the air cap and assists in directing the paint spray.